Image frames may be encoded where a wireless or wired data channel has insufficient bandwidth to timely send the frame data in an uncompressed format. Depending on the available channel bit rate, a given frame maybe compressed to provide a higher or lower quality representation.
With the increase in mobile devices and the prevalence of wireless networking, wireless display capability is experiencing rapid growth. In wireless display technology, a wireless link between a source device and sink display device replaces the typical data cable between computer and monitor. Wireless display protocols are typically peer-to-peer or “direct” and most usage models have a mobile device transmitting media content to be received and displayed by one or more external displays or monitors. In a typical screencasting application for example, a smartphone is wirelessly coupled to one or more external monitors, display panels, televisions, projectors, etc.
Wireless display specifications (e.g., WiDi v3.5 by Intel Corporation, and Wi-Fi Display v1.0 or WFD from the Miracast program of the Wi-Fi Alliance) have been developed for the transmission of compressed graphics/video data and audio data streams over wireless local area networks of sufficient bandwidth. For example, current wireless display technologies utilizing WiFi technology (e.g., 2.4 GHz and 5 GHz radio bands) are capable of streaming encoded full HD video data as well as high fidelity audio data (e.g., 5.1 surround).
In many applications and use cases, frame updates from a source to a sink may arrive in bursts with some frames persisting longer in a display buffer than others as a function of a variable display buffer update frequency. For example, where a GUI active on a source device is screencast to a sink display device, source device power may be saved if a graphics stack executing on the source device renders a new frame of the GUI to the display buffer only as needed to accommodate a scene change (e.g., cursor movement, etc.). A given frame may then persist in the display buffer for multiple screen refresh cycles. Accordingly, the manner in which a source provides such static frames to a sink display device may impact a user's perception and experience with the source and sink devices.